1. Field of the Invention
The present invention relates to a susceptor support portion for supporting a susceptor used at the time of forming an epitaxial film on the surface of a semiconductor wafer and an epitaxial growth apparatus including the susceptor support portion.
2. Description of the Related Art
Generally, epitaxial wafers are manufactured by growing an epitaxial film on a semiconductor wafer, with an epitaxial growth apparatus. The uniformity in the thickness of the epitaxial film is one of qualities of the epitaxial wafer, and a high-quality epitaxial wafer is conditioned on the fact that the distribution of film thickness is in a predetermined range within the surface of the wafer.
Generally, the thickness of an epitaxial film is influenced by the temperature of a semiconductor wafer located below the film. The semiconductor wafer is heated through a susceptor, but a susceptor support portion is present at the rear surface of the susceptor. Due to the presence of the susceptor support portion, a difference occurs between the temperature of a shadowed part of the susceptor support portion of the susceptor, seen from a heating apparatus disposed downward, and the temperature of the other parts, which leads to a problem that the temperature of the entirety of the susceptor does not become uniform.
In this regard, for example, JP-A-10-335435 and JP-A-2011-108765 disclose a technique in which a susceptor support portion is formed of a transparent material such as quartz glass. However, even when the susceptor support portion is formed of a transparent material, it has been difficult to solve the above-mentioned problem.
Further, there is also a problem in that a susceptor is deformed due to exposure to a high-temperature environment, and the temperature of the entirety of the susceptor does not become uniform. In this regard, JP-A-2011-108765 discloses a technique in which a force for supporting a susceptor is strengthened by setting the number of arms of the susceptor support portion to four or more, and the susceptor is prevented from being deformed.
However, an increase in the number of arms of the susceptor support portion leads to an increase in a part shadowed by the susceptor support portion.